Early Buddhist Schools

The early Buddhist schools are those schools into which the Buddhist monastic saṅgha initially split, due originally to differences in vinaya, and later also due to doctrinal differences and geographical separation of groups of monks.

The original saṅgha split into the first early schools (generally believed to be the Sthaviravādins and the Mahāsaṃghikas) a significant number of years after the death of Gautama Buddha. According to scholar Collett Cox "most scholars would agree that even though the roots of the earliest recognized groups predate Aśoka, their actual separation did not occur until after his death." Later, these first early schools split into further divisions such as the Sarvāstivādins and the Dharmaguptakas, and ended up numbering, traditionally, about 18 or 20 schools. In fact, there are several overlapping lists of 18 schools preserved in the Buddhist tradition, totalling about twice as many, though some may be alternative names. It is thought likely that the number is merely conventional.

The schools sometimes split over ideological differences concerning the "real" meaning of teachings in the Suttapiṭaka, and sometimes over disagreement concerning the proper observance of vinaya. These ideologies became embedded in large works such as the Abhidhammas and commentaries. Comparison of existing versions of the Suttapiṭaka of various sects shows evidence that ideologies from the Abhidhammas sometimes found their way back into the Suttapiṭakas, to support the statements made in those Abhidhammas.